Line a 20 x 30cm rectangular tin with baking parchment. Blueberry biscuit bake the biscuits in a food processor and blitz to a fine crumb. Add the butter and blitz again to combine. Tip into the tin, press down firmly with the back of a spoon to cover the base, then bake for 10 mins.
Meanwhile, tip 25g of the sugar and the blueberries into a small pan. Mix the cornflour with 1 tbsp cold water and add this to the pan. Heat gently until the sugar dissolves. Increase the heat and bubble for 1-2 mins until saucy. In a large bowl, whisk the cream cheese with an electric hand-held whisk until smooth.
